Flux Observer with On-Line Identification of Resistance for DC-based DFIG

A stator flux observer based on resistance on-line identification is proposed for DC-based DFIG system. The stator and rotor sides of the DFIG are respectively connected with stator side converter (SSC) and rotor side converter (RSC), and then connected to DC grid. A stator current sliding mode observer based on resistance online identification is designed to estimate the stator flux in α/β reference frame. The structure of the observer is simple and easy to realize. It has a wide range of practicability for the double controllable DC converter DFIG system whose stator side is no longer subject to the power grid, especially when the field orientation control is needed. The stability of the observer is proved by Lyapunov theory. The simulation results are compared with the traditional stator flux voltage model to verify the effectiveness of the flux estimation method.